Doujinshi are little parodies of a manga in general (of Fruits Basket here) written and drawn by fans. Most of the time they are published and sold by their author.
There are many doujinshi pertaining to FB but we will only post a few of them here, as they are quite difficult to find, and often too hentai to be posted.
Raw scans come from the Red Butterfly website, which I advise you to visit.
Warning : from now on the scans will only be available in .rar files, you will need Winrar to unzip/view them.